FIG. 1 is a functional block diagram of a prior art digital television set. The tuner 102 receives television signals generated by the television signal source 101. The television signals processed by the demodulator 103, demultiplexer 104 and then sent to the Digital Signal Processor (DSP) 111, the image decoder 112 and data decoder 113 for further processing and decoding by the Digital Signal Processor (DSP) 111, the image decoder 112 and data decoder 113. The decoded sound data is played on the speakers 131 and the image data is further processed by the graphics processor 121 and displayed on the display 132.
The received television signal is also decoded by the data decoder to be further processed by the central processing unit (CPU) 122. Commands by users via a user interface 140, e.g. a remote control 141 or panel buttons 142 on a digital television are also processed by CPU 122 then stored in the DRAM 151. A flash memory 152 stores programs and associated in generation.
On Screen Display (OSD) provides real-time operating information on screen when user switches channels, tuning up volume and adjusting display properties. The operating information, including special fonts and icons, is displayed on any specific locations on the television screen. To realize the OSD, large amount of font and data or icons need to be stored in the flash memory 152. The CPU 122 controls the font, data and icons. The CPU 122 transfers the font, data and icons to DRAM 151 for graphics processor 121.
For example, in the case of font, font files with various sizes are required to support the OSD function, which consumes large storage space of the flash memory 152. Along with the development of large size panel display and high image display resolution, bitmap font files require large storage space of the flash memory 152. Consequently, the product cost is increased. Therefore, it is a primary goal of the present invention to support high quality font display at low cost.